Hey all, what would be the max speed of a Z in 3rd at 5800 rpm with the stock 3.42 gears? reason i ask is b/c my car redlines around 120 mph and really doesnt want too accelerate past it. will the 4L60E shift to 4, the OD gear at WOT??. Could it be that my car has one of those speed governors? it has the 155mph speedo. If so is there a way to see that setting with auto-tap?? or is my tranny starting to die? Thanks for your help.

 

If your car was optioned new without speed rated tires then it does indeed have a 118 mph speed limiter.

 

I have no idea, how do i tell, will the governor cause it to redline at 120?....it was bought used

 

If it has a speed limitter it will kill the motor when reaching the cut off speed and when it drops down a few mph then it will come back on. If you keep on it, it will go off agian when you reach the cut off speed.

And before you desicde to go that fast you need to check the speed rating on your tires and Make sure the air pressure is correct. Ever watch Cops? Wonder why all those cars you see are always blowing tires? Most are do to improper tire inflation and others are going over the speed rating of the tires.. You can run faster than the rateing but not for long periods of time.


Keep Safe

 

hmmm, doesnt do that, it just seems to get up to 5800 rpm at about 120mph and just stay there. So I assume my trans is supposed to get to the next gear but isnt doing it. Im thinking my trans is a bit worn, maybe the 3-4 clutches?? but then again Im no trans expert and hence my post....

 

funina91ss is dead on don't take that car up to speeds like that until you check tire pressure and speed rating.

ok with that said put the car in D and run it up to around 60 or so then put it in to OVERDrive and see if you get a shift... if you do get a shift put it back in to D "at a lower speed then run it up until you get to close to red line then put the shifter in to Over Drive and see if you get a shift. if you dont then there could be a number of problems.

3-4 shift at wot is very hard on the 4l60e... it's not a good idea to do this alot... you will kill 4th.

 

hey guys, thanks for the warning.....tires have 36psi all around and speed rating of H, so they're good up too about 130mph. I dont know what tires came with the car from the factory, those were on the car when i bought it though, almost 2yrs ago. I will try the cruise at 60 in D and shift to OD and see what happens.
Just out of curiosity, what would be some problems if it doesnt shift?? also just for my own knowledge, what gear does a 4l60e be in at 120? I dont plan on gettin her up to that speed. just asking for future reference.

 

Well at WOT the car should be around 120 the end of 3rd gear, but it will depend on the rear gear. 3.23's shift points are different then 2.73's so really you need to know what your gear is. I'm sure one of the other guys know the stock shift points@WOT

I’m not sure where it is on the lt1's but if you can find the build codes look for gu2 or gu3. gu3 = 3.23's gu2 = 2.73's. If you cant find that look at the drive shaft. Steel = 2.73's aluminum = 3.32’s or for the no brainier; rust = 2.73’s shiny = 3.23’s


Under normal driving conditions you will be pulling around 2000 rpm’s at 60/65 mph. also you should be able to feel each shift. Just watch for 3 rpm drops 1-2 2-3 3-4 you might also see what feel like another shift but that’s just the converter locking up in 4th.

If you are having problem with 4th it could be low fluid, burnt clutches, valve body problem “stuck valve”. Check fluid once the car is warmed up in park on level ground, fluid should be at the top of the hot mark after driving 15 miles or so. Fluid just does not leak out under normal conditions so if you are low check for leaks. Also while you’re checking the fluid level try smelling it for a burnt smell also look for a discoloration, it should be a red or pink, if it’s brown and smells burnt then you might want to try a fluid change. If you want to go all out some places will do a complete system flush that will insure you get all old fluid out. The 4l60e holds around 11qt and with just a pan drop you will only be getting about 5qt out. So the flash is the best way to go but will cost around $50 or more.

 

You can,t tell by the driveshaft.
My car came with the performance axle ratio, 3.23s and I had the stock steel drive shaft. Its a 1LE shaft now but it came stock with the steel one.